The Commonwealth Prime Minister on May 12 began shaping the final communiqué of their 10-day world-ranging discussions, which have covered Summit prospects, international trading problems and constitutional developments. The 11 delegates — from Britain, Canada, Australia, New Zealand, South Africa, India, Pakistan, Ceylon, Ghana, Malaya, and the Rhodesia-Nyasaland Federation — had before them a draft prepared by their senior officials. Conference sources said that the officials had referred to their leaders the controversial question of what references, if any, should be made to the issue of apartheid and racial discrimination, which has bedevilled the statesmen since the talks began on May 3.